Cellular telephone anti-fraud system

DETAILED DESCRIPTION In a first form of the invention, a transmitter identification device includes a plurality of transmitters each for generating a transmitter signal with internal data traits and external signal traits.
A receiver located remote from the transmitters receives the transmitter signal.
A characterizing device connected to the receiver characterizes one of the transmitters and generates a plurality of characterizing signals for the one transmitter.
The characterizing device generates the plurality of characterizing signals by measuring features of the external signal traits of said one of said transmitters from at least one of a first category including variations of specified parameters of said one of said transmitter, and a second category including variations in non-specified parameters.
A converter connected to the characterizing device converts the plurality of characterizing signals into a security pattern.
The security pattern is used to identify said one of said transmitters.
In another feature of the invention, a historic security pattern storing device stores historic security patterns for a plurality of transmitters.
A first comparator connected to the converter and the historic security pattern storing device compares the security pattern of said one of said transmitters to said plurality of historic security patterns stored in said historic security pattern storing device.
It is still another feature of the invention that the first comparator generates a confidence level indicating a likelihood that one of said transmitters also generated the historic security pattern.
In still another feature of the invention, the confidence level generated by the first comparator indicates a mismatch condition, a possible mismatch condition, and a match condition.
In another embodiment, apparatus for identifying wireless subscriber units and for granting or denying access to a subscriber service includes a plurality of wireless subscriber units each for generating a wireless subscriber signal including internal data traits and external signal traits and for receiving a receiver/transmitter signal